This invention relates in general to transferring information between a main storage and input/output devices in a data processing system, and in particular to a method for increasing the information transferring capacity of the data processing system including techniques for reducing the number of operations required to perform certain I/O functions and for increasing the amounts and types of information that may be transferred during operations.
In a network computing environment, multitudes of commands and requests for retrieval and storage of data are processed every second. To properly address the complexity of routing these commands and requests, a number of different resolutions have been implemented. In some data processing architectures, such as International Business Machines Enterprise System Architecture/390 (Enterprise System Architecture/390 is a registered trademark of International Business Machines Corporation), a channel subsystem is utilized to pass information between the main storage and input/output (I/O) devices. The channel subsystem includes one or more channel paths, each including one or more channels and one or more control units. Recently developed technologies such as the International Business Machines ESCON switch (ESCON is a registered trademark of International Business Machines Corporation), connect the I/O devices to the main memory through the control units using legacy channels to support the data transfer there between.
But as the technology improves, the performance of new system processors will require many more legacy channels than are presently in use to support the resulting increase of information transfer in the data processing systems. Current architectural constraints make the addition of such legacy channels an expensive proposition. A further challenge is to provide the link data rate required to support the data rates of new I/O devices such as DASDs and Tapes. In this case, simply adding more legacy channels does not adequately address the problem. A new architecture is needed that can scale up to the higher link speeds needed for normal transaction processing. Therefore, any new proposed architecture, must include a capacity to accommodate higher bandwidth channel links such as Fibre Channel links while providing better data rates and higher link speeds.
This application is being filed at the same time as a related application, Ser. No. 09/379,129, now U.S. Pat. No. 6,338,083.
This application incorporates by reference the following patent: U.S. Pat. No. 5,526,484 to Casper et. al.
The present invention provides for a method of transferring information in a network computing system environment. The network environment includes a main storage coupled to a channel subsystem with a plurality of channels which is in processing communication with a control unit capable of coupling to a plurality of input/output devices. At first the packets of data are sent concurrently to and from the main storage. Next execution of certain channel functions are transferred to the control unit so that certain commands can be combined with the data packets in one sequence. Finally only one start data command and only one end command notification needs to be sent before and after a plurality of data packets is transferred respectively. In one embodiment of the present invention a plurality of channel control words or CCWs are pipelined together in order to send associated processed data and commands to the control units without any need for interlocking responses from the control units. Also the CCWs can be chained together so that a step of requiring all intermediate Status Sequences is eliminated. In another embodiment of the present invention a fabric or a plurality of optical fiber and switches is also used in processing communication with the control units and the channels. The network environment can also include a storage control element in processing communication with the main storage and channel subsystem and coupled to at least one central processing unit.
In yet another embodiment another method is employed in the same network computing system environment having the steps of: fetching said command from said main storage; fetching associated data from said main storage; and transferring said fetched command along with said fetched associated data to said control unit.